This invention relates to heat exchanger attachments in general, and specifically to a plastic attachment bracket for a metal heat exchanger tank that is fixed to the tank with only a press fit, at any position desired along the length of the tank, with only a press fit and no other fasteners.
Some automotive heat exchangers, such as radiators, have a molded plastic header tanks on two sides (or top and bottom) in which it is relatively simple to mold many additional features, such as attachment brackets to allow the tanks, and thereby the entire radiator, to be installed to the vehicle body structure. Other front mounted heat exchangers, such as condensers, typically have stamped or extruded metal header tanks in which it is more difficult to integrally form attachment brackets. Consequently, separate brackets are generally first fixed to the header tanks, and these are later used to install the tanks and heat exchanger to the vehicle body, typically by bolts and vibration isolating grommets. The separate attachment brackets are fixed to the heat exchanger tanks most often by brazing, either a separate brazing step (flame brazing) after the main core is furnace brazed, or as part of the furnace brazing process. In the latter case, the bracket is often designed to make a light snap fit around the tank, in clothespin fashion, with just enough retention force to hold it in place until it can be permanently secured by brazing.
As an alternative, metal heat exchanger tanks, such as condenser tanks, made by extrusion can be formed with an integral lengthwise flange extending out from the side which, to an extent, can be used directly as an attachment bracket. This generally entails cutting away much or most of the length and leaving behind discrete tab like remnants, which can be used as bolt hole supports or which can be slipped into to hooks integrally molded on a radiator tank. This is of limited utility, since such an extruded flange, unlike a molded plastic part, cannot be molded with a large width or with any complex features, apart from holes, notches and the like cut in after extrusion.
To date, there has been some limited use and disclosure of molded plastic attachment brackets secured to metal heat exchangers, and then used to install the heat exchanger to the vehicle body, either directly or indirectly. As shown in U.S. Pat. No. 6,207,737, FIG. 5, known plastic brackets of this type are secured to one of the ends of the tank, that is, to one of the four corners of the basically rectangular frame of the heat exchanger core. The corner provides a convenient anchoring point for such a bracket, with both vertical and horizontal surface area available for the bracket to grip onto. In other cases, however, it is desired to not be limited to the corners, and to be able to place an attachment bracket anywhere along the length of the tank.
The invention provides a molded plastic attachment bracket that can be secured anywhere along the length of a metal heat exchanger tank, combining all the benefits of a plastic molded part with holding strength equal to that of a brazed on metal attachment bracket.
In the preferred embodiment disclosed, a condenser of basically conventional shape and design has a pair of extruded aluminum header tanks, extruded symmetrically along a longitudinal axis, and each of which has a flat side face. Extruded integrally with the tank is an elongated flange, extending outwardly from the tank side face substantially perpendicular thereto, with a relatively short front face and a longer back face that is flush with the back of the tank. The flange is stamped after extruding with several narrow, open notches, perpendicular to the axis of the tank, and a number of indentations in the form of small windows adjacent to the notches. These cooperate with features of the bracket to secure it to the tank.
A plastic attachment bracket is provided for at each tank, a molded plastic part having an outboard ear adapted to be bolted to a vehicle body structure and an inboard pocket that is fixed to the tank flange by a press fit. The narrow, long bracket pocket is defined by a back wall that slidably engages the back face of the tank flange and the flush back of the tank, and a front wall that slidably engages the flange front face. The pocket front face turns out in a perpendicular footer that is abuttable with the flat side face of the tank. This allows the bracket pocket to be pressed over the tank flange closely until the footer abuts the tank. At a point that registers with each flange notch, the pocket walls are bridged by a narrow but rigid cross beam that fits closely into each notch. The pocket back wall is also molded with a series of resilient fingers, running toward the top of the pocket, each of which has a barbed end that registers with a window and, in a free state, extends into the pocket space.
The bracket is fixed to the tank by pushing the pocket over the flange in a direction generally normal to the tank axis. The flange back and front faces slide along respectively along the pocket front and back walls, as the cross beams insert into the notches and the resilient fingers are flexed out of their free state. As the pocket footer abuts the tank side face, the barbed fingers snap into to the flange windows, and the cross beams are fully inserted into the notches. With insertion complete, bracket cannot be pushed farther onto the tank, and is prevented from pulling away from the tank by the capture the resilient finger barbs in the flange windows. The bracket cannot shift in either longitudinal direction, by virtue of the insertion of the cross beams in the notches. As far as the bracket twisting around the axis of the tank, the large area of surface contact between the pocket back wall and tank back face prevents twisting in one direction, while the abutment of the pocket footer and tank side face provides the same twisting resistance in the other direction. As far as twisting of the bracket normal to the tank axis, the close fit of the flange pocket and cross beams over and into the flange and notches provides a strong, solid resistance. The net effect is that the bracket is very solidly retained to the tank, and it can be so secured to the tank anywhere along its length, not just to the corners.